Editing List of unidentified species

{{Status|Canon}}
[[File:Alien ship 2.png|thumb|300px|A look at a crashed [[Unidentified alien vessel|vessel]] from an unidentified species, responsible for landing on Installation 04.]]
During its history, the [[Milky Way]] galaxy has played host to many intelligent forms of alien life. While many can be grouped under the wider banners of the [[Forerunner]] [[Ecumene]], the [[Covenant]] empire or the auspices of the [[Unified Earth Government]] for [[human]]ity, many alien encounters have been recorded with no currently-known species responsible.

==Overview==
===Forerunner indexing===
According to a [[Catalog]], before the firing of the [[Halo Array]] on [[97,445 BCE]], the [[Librarian]] studied and favored at least 123 species across three million worlds in regions the Forerunners explored in the [[Milky Way]] galaxy. The Catalog was uncertain however how many the Librarian aimed to preserve.{{Ref/Novel|Id=HSS2|Sil|String=2}} While many sentient species were ultimately indexed and reintroduced, many of them did not reach Tier 7 of the [[Technological Achievement Tiers]] after the firing of the Halo array, where only a handful were encountered by [[Human]]ity in the [[Orion Arm]] of the galaxy, and not every species that were in the [[Covenant]] were cataloged by the [[United Nations Space Command]], with even the Covenant client species keeping few records of their affairs with them.{{Ref/Site|Id=HWNCF66|URL=https://www.halowaypoint.com/en-us/news/canon-fodder-bulkhead-banter|Site=Halo Waypoint|Section=News, Canon Fodder|Page=Bulkhead Banter (Issue 66)|D=16|M=1|Y=2021|LocalArchive=https://archives.halopedia.org/waypoint/www.halowaypoint.com/en-us/news/canon-fodder-bulkhead-banter.html}}

==Locations==
===Great dense cloud===
Following the [[Great Purification|firing]] of the Halo Array, a final communication was heard by [[343 Guilty Spark]] at [[Installation 04]] from a "great dense cloud". This was sent from a species that just managed to send out their first communications out from their home system. This species was not encountered by the Forerunners or Flood; and ultimately was not indexed by the Librarian for reintroduction. Guilty Spark did not understand their message, but presumed it was hopeful signals. After the Halo's pulse hit the cloud, the communication stopped.{{Ref/Novel|Id=HSS39|Sil|Chapter=string 39}}

===Installation 04 (Alpha Halo)===
Over its operational lifespan, several unidentified visitors have found their way to Halo Installation 04.

====Crashed ship====
{{Main|Unidentified alien vessel}}
Around 40,000 BCE{{Ref/Game|Id=HCEAT6|HCEA|Part=[[Terminal (Halo: Combat Evolved Anniversary)|Terminals]]|Terminal 6}} (50,000 years following the firing of the array), an [[Unidentified alien vessel]] crashed on the ring during an experiment [[343 Guilty Spark]] conducted on the Halo.{{Ref/Game|Id=HCEAT4|HCEA|Part=Terminals|Terminal 4}}{{Ref/Game|Id=HCEAT5|HCEA|Part=Terminals|Terminal 5}} None of the ship's occupants attempted to leave the vessel's crash site or attempt contact, leading Guilty Spark to build a sarcophagus around the vessel. Ultimately, the Monitor was hopeful for the next species to arrive on the ring.{{Ref/Reuse|HCEAT6}}
<gallery>
File:Alien ship 2.png|Unidentified ship.
</gallery>

====Visitors to the ring====
During the [[Battle of Installation 04]], 343 Guilty Spark noted in logs made during the battle that the [[Covenant]] landing on the ring and seeking something was similar to another alien species who previously arrived at the ring, recorded what they saw and left.{{Ref/Game|H2|Part=Limited Edition|[[Conversations from the Universe]] - 343 GUILTY SPARK – EXTRACTED/TRANSMITTED/ VOLUNTEERED FROM LOG}} These visits ultimately lead to 343 Guilty Spark changing his excitement at the prospect of meeting an alien species to defensive; threatening ships that trespassed near the ring including the {{UNSCShip|Pillar of Autumn}} in [[2552]].{{Ref/Game|Id=HCEAT1|HCEA|Part=Terminals|Terminal 1}}

===Installation 05 (Delta Halo)===
It has been suggested that outside meddling may have caused the breach which lead to a [[Flood]] outbreak at the installation's containment facility, culminating in the outbreak and eventual formation of a [[Gravemind]] on Installation 05.{{Ref/Site|Id=HWULDelta|URL=https://www.halowaypoint.com/en-us/universe/locations/delta-halo|Site=Halo Waypoint|Section=Universe, Locations|Page=Delta Halo|D=5|M=3|Y=2021|LocalArchive=https://archives.halopedia.org/waypoint/www.halowaypoint.com/en-us/universe/locations/delta-halo.html}}

===System of Miasmic Giants===
Around [[851 BCE]], the [[Sangheili]] [['Crecka]] recalled a event that happened "many cycles ago" in the System of Miasmic Giants where a hostile species attacked a vessel he served on. During the attack, 'Crecka was the last survivor and managed to escape by piloting the ship randomly though slipspace. According to 'Crecka, the species did not speak a civilized tongue.{{Ref/Novel|Id=HBC1|BC|Section=Part One: A Place of Refuge|Chapter=1}}

===The Refuge===
According to [[Bal'Tol 'Xellus]], an alien prisoner from a far off planet found The Refuge, where it taught 'Xellus' ancestors a meditation that would be passed on for generations until it was passed onto them.{{Ref/Novel|Id=HBCC15|BC|Section=Part Two: An Invitation to the Dance of Chaos|Chapter=15}}

===Line Installation 9-12===
Among the debris found at [[Line Installation 9-12]] includes a number of ships belonging to species not known to be Human or Covenant client species.{{Ref/Book|Id=H4EVGLWreckage|H4EVG|Section=Locations, War Games|Page=221 (Wreckage)}}

===Netherop===
{{Main|Netherop species}}
During the time of the [[Forerunner-Precursor war]], the planet of [[Netherop]] hosted a Tier 6 species.{{Ref/Novel|Id=Out17|Out|Chapter=17}} The species was assumed extinct by [[John-117]].{{Ref/Novel|Id=HOC12|Oblv|Chapter=12}}
<gallery>
File:HOut CoverArt.jpg|[[Oath Warden]] [[Crei 'Ayomuu]], [[Spartan-IV]] [[Olympia Vale]], and [[Arbiter]] [[Thel 'Vadam]] among the ruins on Netherop.
</gallery>

===Karava===
This species was discovered by the Covenant on their homeworld of [[Karava]]. When encountered, they refused to give in to the Covenant's demands - resulting in the Covenant deploying 300 {{Pattern|N'weo|Gigas}} fighters against the species, wiping it out completely in a total genocide.{{Ref/Book|Id=Enc22p289|Enc22|Page=289}}

===Unknown skycrypt===
On a world that was controlled by the Forerunners, numerous [[skycrypt]]s were constructed to keep threats contained. One of these platforms had a security breach leading to the inhabitant escaping.{{Ref/Site|Id=HWTHB11911|URL=http://blogs.halowaypoint.com/Headlines/post/2011/11/09/The-Halo-Bulletin-11911-.aspx|Site=Halo Waypoint|Section=News|Page=The Halo Bulletin: 11.9.11|D=30|M=4|Y=2013}}{{Ref/Map|HR|Solitary}}{{Ref/Book|Enc22|Page=327}}
<gallery>
File:Solitary 052.jpg|A broken "window" on the confinement platform.
File:HReach-Solitary-Prison-Forerunner.jpg|The confinement platform.
</gallery>

===October 10 aggressors===
{{Main|Battle of October 10}}
On [[2552##October|October 10, 2552]] (ten days prior to the outbreak of the [[Battle for Earth]]), a series of twelve unknown starships entered the [[Sol system]] broadcasting outdated civilian [[Identification friend or foe|IFF]] codes and were engaged by a [[UNSC Navy]] task force. [[Battle Group Rhino]] engaged the aggressors on October 10, with eleven immediately making unauthorised slipspace transits outside of the Sol system, and the single remaining vessel engaging. {{UNSCShip|Totem Lake}} was lost with all hands in the battle after suffering numerous hull breaches and [[Naval boarding|boarding]] actions, before Battle Group Rhino fell back to [[Phase Line Alpha]], over [[Enceladus]].{{Ref/Generic|[[Halo Legendary Crate]]|[[Halo Legendary Crate/Data Drops|Data Drop 2]]}}

===Underground species===
A handful of lost burrowing species and mining civilizations across the [[Orion Arm]] had been discovered by humanity by [[2559]].{{Ref/Novel|Out|Chapter=3}}

==Gallery==
<gallery>
File:HINF Concept Machamp.jpg|Early concept for ''[[Halo Infinite]]'' depicting a large, armored unknown alien species with four arms and vaguely reptilian features.
</gallery>

==Sources==
{{Ref/Sources}}

{{Navbox/Species}}
[[Category:Sapient species]]